DE2519389B2 - Catalyst with a nickel component and a tungsten component on a silicon dioxide-aluminum oxide carrier and its use - Google Patents

Description

The invention relates to a catalyst with a nickel component and a tungsten component on a silica-alumina support obtained by making the support from a silica supplying compound and from an aluminum oxide supplying compound and optionally Washing, drying and calcining of the resulting carrier, impregnating the carrier with the nickel component and the tungsten component, in particular using an aqueous solution a nickel salt and a tungsten salt, and drying and calcining the impregnated carrier at elevated temperatures in an oxidizing atmosphere.

The catalyst is particularly intended for the hydrocracking of hydrocarbons.

For the destructive hydrogenation or hydrocracking of hydrocarbons commonly used in relatively high temperatures and pressures is carried out, especially when processing high-boiling hydrocarbon oils such as coal tar or high-boiling petroleum fractions, e.g. B. gas oils or topped crude oils, numerous catalyst compositions have been reported. Mostly included they or they consist of metal components from group VIII of the periodic table, often to-

together with metal components from group VI «of the periodic table. If at the same time as hydrocracking hydrofining, d. H. especially desulfurization and nitrogen removal are to be used as metal components preferably nickel and molybdenum or nickel and Tungsten used. These metal components are usually in association with both Porous carriers of amorphous or zeolitic form comprising aluminum oxide and silicon dioxide Character applied.

Two different working methods are primarily used to produce the catalyst. Mostly preferred is an impregnation method in which a previously calcined preformed carrier material, which has been precipitated in a multi-stage process, with soluble Compounds of the nickel component and, if used, the component of group VIa of the periodic table impregnated and the impregnated material then at elevated temperature, e.g. B. about 149 ° C, dried and at a further elevated temperature, e.g. B. about 593 ° C, is oxidized. With the other All the catalyst components, including those of the support material, are used in common failed.

It has been shown that catalysts with a nickel component and a tungsten component on a silica-alumina carrier are particularly favorable. Such catalysts and Appropriate manufacturing methods have also been described in various embodiments.

For example, US-PS 3216922 describes a carbon-hydrogen conversion catalyst, especially for the hydrocracking of hydrocarbons containing at least one metal from groups VIa and VIII of the periodic table in association with a solid acidic carrier material which is a mixture of Silica and alumina in a molar ratio of about 5 moles of silica per mole of alumina comprises, wherein the silica is formed from a silica hydrogel that is prior to the association with the alumina for a period of at least one hour at a pH in the range of about 3 to about 8 has been aged.

The prescribed molar ratio of about 5 moles of silicon dioxide per mole of aluminum oxide for this catalyst, d. H. a composition of about 75% silica and 25% alumina in the sense of the formation of an acidic support material sought there, a catalyst with a relatively high silica content in the carrier. The combination of a nickel component with a Tungsten component is not specifically mentioned in the information about this known catalyst, rather, other metal components or metal component combinations, such as platinum, Palladium, nickel, molybdenum or mixtures thereof, shown to be preferred.

GB-PS 1 183 778 describes a process for the hydrocracking of a hydrocarbon oil with a Boiling range entirely or essentially above 350 ° C, at which the hydrocarbon oil under hydrocracking conditions at elevated temperature and pressure with a hydrocracking catalyst that has been made

by first precipitating a silica gel from an aqueous solution containing silicate ions, Aging of the silica gel at elevated temperature, precipitation of aluminum hydroxide on the aged gel by adding an aqueous aluminum nitrate solution and an alkaline solution in such amounts that the silicon dioxide / aluminum oxide weight ratio in the final support is in the range of 0.6: 1 to 1.8: 1, separation, Drying and calcination of the resulting precipitation product of aluminum hydroxide on silicon dioxide at a temperature of at least 400 ° C and subsequent application of an or several salts of a metal or metals of the sixth and / or eighth group (s) of the periodic table onto the catalyst support and then calcining the metal salt or metal salts having carrier.

In the manufacture of this known catalyst, therefore, is used for the preparation of the silicon dioxide-aluminum oxide support material a relatively broad range of silica to alumina ratio viewed as generally useful and also with regard to the catalytically active metal component (s) In addition to nickel and tungsten, there is a wide range with numerous other metal components and metal component combinations left open. Furthermore, the carrier material must after the specified, two-stage precipitation method with precipitation first of the silicon dioxide gel, aging of the gel at an elevated temperature and then separately Precipitation of aluminum hydroxide on the aged gel by adding an aqueous aluminum nitrate solution and an alkaline reacting solution. This is relatively cumbersome and laborious. In the case of such a precipitation, the aluminum hydroxide must also affect the aged Silicon dioxide gel the production of an inhomogeneous carrier material must be accepted, as a homogeneous enforcement of the components is probably not possible, which naturally increases the risk of generation a not completely uniform catalyst.

The known catalysts lead to useful results, but they are effective in their effectiveness or production method is not yet completely satisfactory and it is therefore because of their large technical and economic importance constantly a keen interest in technology according to information Catalysts which are easy to manufacture and whose effectiveness is further improved.

The invention is accordingly based on the object of providing a catalyst of the type indicated at the outset To create a kind that is characterized by a particularly high level of activity and is easy to do without accepting it laborious or expensive measures is to be produced.

To achieve this object, the invention relates to a catalyst with a nickel component and a tungsten component on a silica-alumina carrier, obtained by preparing the support from a compound which yields silicon dioxide and from an aluminum oxide delivering compound and optionally washing, drying and calcining of the resulting Carrier, impregnation of the carrier with the nickel component and the tungsten component, in particular using an aqueous solution of

nes nickel salt and a tungsten salt, and drying and calcining the impregnated carrier at elevated temperatures in an oxidizing atmosphere, which is characterized by that it is produced by joint gelling of the compound which yields silicon dioxide and the aluminum oxide delivering compound in such a proportion that the finished carrier 43 to 57 percent by weight Contains alumina and 57 to 43 percent by weight silica, impregnating the obtained Carrier with 2 to K) percent by weight of the nickel component and 8 to 20 percent by weight of the tungsten component, calculated as metals and based on the final catalyst composition, drying the impregnated support at a temperature of 93 to 260 ° C and calcining at a temperature from 371 to 649 ° C and reduce if necessary at a temperature of 371 to 538 ° C in the presence produced by hydrogen.

Surprisingly, it has been found that if the prescribed according to the invention are adhered to special selection and combination of measures with joint gelation of the silicon dioxide supplying compound the aluminum oxide supplying compound in the specified proportions, in connection with the further marked manufacturing measures, a silicon dioxide-aluminum oxide-nickel-tungsten catalyst is obtained, which is characterized by particularly good activity, as well as by the results of the later The example carried out is proven with comparative studies. The joint gelling of the silicon dioxide supplying compound and the alumina supplying compound in the prescribed As is readily apparent, the quantity ratio can be carried out very easily and reliably, for example according to the known oil drop method; a comparatively laborious and time-consuming, two-stage precipitation method with first precipitation of the silicon dioxide gel, Aging of the gel at elevated temperature and then separate precipitation of aluminum hydroxide on the aged gel by adding an aqueous aluminum nitrate solution and an alkaline one reactive solution, as in the operation of GB-PS 1 183 778 explained above, is not required. Furthermore, the prescribed joint gelation ensures the production of a homogeneous one Support material, which is the basis for a completely uniform catalyst and the risk of Excludes irregularities in the catalyst.

Features and preferred embodiments of the invention are further explained below.

The mixed-gelled silica-alumina catalyst support produced by joint gelling is preferably in the xerogel state, i. H. dried enough to make the usual microporous To have structure and accordingly a sufficiently accessible surface. It can also be a mixed gelled silica-alumina carrier be used, which is only available at a comparatively low temperature, e.g. B. 125 ° C has been dried and still contains considerable amounts of water, but then drying must in any case be sufficient, to remove substantially all of the water from the pores of the support.

The catalyst is suitable e.g. B. to bring about the greatest possible production of liquefied gas in Propane / butane range from heavy gasoline or other

ren in the gasoline range boiling distillates and for the conversion of heavier feedstocks, z. B. Kerosene, light gas oils, heavy gas oils and black oils, so named for their usually deep dark to black color, in lower-boiling products that are liquid under normal conditions, such as petrol, Kerosinc, middle distillates and lubricating oils.

As is customary in the field of catalysis, information about the catalytically active metal (s) State forms as a metallic element and as a connection, e.g. B. in the form of an oxide, sulfide or halides. Regardless of the state in which the metal components are actually in the individual case are present, the content information is calculated as if the metal components in elemental metallic Form.

The preferred procedure for preparing the silica-alumina mixed gel carrier is the well-known oil drop method, which produces the carrier and thus the catalyst in the form relatively large balls permitted. For example, an alumina sol is used for delivery of the aluminum oxide is used, mixed with an acidified waterglass solution which supplies the silicon dioxide and further a gelling agent, e.g. B. urea, hexamethylenetetramine or a mixture of it, mixed in. The mixture is then, while it is still below the gelation temperature, for example by means of a nozzle or rotating disk in the form of droplets in a gel at the gelling temperature held hot oil bath. The droplets solidify as they pass through the oil bath to spherical gel particles. The alumina sol is preferably prepared by Aluminum granules with deionized water and hydrochloric acid in sufficient quantity to make up one part to digest the metallic aluminum and to form the desired sol, to be mixed. One a suitable rate of reaction results if the mixture is kept at about the reflux temperature.

The resulting spherical glass particles are then, usually in the oil bath, at least K) to 16 Hours and then aged in an alkaline medium for at least 3 to about 10 hours and finally washed with water. For a gulc gelation of the A good temperature in the oil bath as well as proper aging of the gel balls should usually be above about 48 ° C are maintained. On the other hand, at temperatures of around 99 ° C one tends to Too rapid release of gases leading to cracking or other weakening of the balls. By overpressure during the molding and aging steps so that the water is kept in the liquid phase, a higher temperature can be applied, often with improved results. If the gel pieces at Be aged above atmospheric pressure, no alkaline aging step is required.

The balls are then washed with water, preferably with water containing some ammonium hydroxide and / or contains ammonium nitrate. After that, the balls are at a temperature of about Dried at 93 to 3 16 ° C for about 2 to 24 hours or more and then calcined at a temperature of about 427 to 760 "C for about 2 to 12 hours or more.

The nickel component and the tungsten componentc are carried out according to some appropriate impregnation method, preferably with joint impregnation on the mixed-gel silicon dioxide-aluminum oxide carrier upset. For example, the carrier in an aqueous impregnation solution containing a soluble nickel salt and a contains soluble tungsten salt, can be swallowed, immersed or suspended in it. Preferably the carrier is placed in the impregnation solution and the latter then, for example in a steam-heated one Rotary dryer, evaporated to dryness. The amount and concentration of the impregnation solution will be like this chosen that the final catalyst composition is 2 to K) and preferably 7 to 9 percent by weight Nickel and 8 to 20 and preferably 17 to 19 percent by weight tungsten.

The impregnated carrier is then, usually 1 to K) hours, at a temperature of 93 to Dried at 260 ° C. The subsequent calcination takes place in an oxidizing atmosphere at a Temperature from 371 to 649 ° C. As an oxidizing atmosphere air is expediently used, but other gases, the molecular oxygen, can also be used included, can be used.

After calcination, the catalyst is usually 0.5 to 10 hours at a temperature of 371 to 538 ° C reduced in the presence of hydrogen. The catalyst can also be in sulfided form used and for this purpose, after the reduction, subjected to sulphidation by adding hydrogen sulphide or brings another sulfur-containing compound into contact with the catalyst, expedient at a temperature of 260 to 593 ° C. The sulfidation is preferably carried out by a stream of hydrogen, which contains 1 to over 20 percent by volume of hydrogen sulfide, at temperatures of 260 to 593 ° C passes through the catalyst. A useful range of sulfur content is 0.05 up to 1 percent by weight sulfur, based on the elemental state. If those intended for hydrocracking Petroleum hydrocarbons contain sulfur compounds, sulphidation can also take place on site and place at the beginning of the hydrocracking process.

The catalyst is preferably used in the form of a fixed bed in the reaction zone. The hydrocarbon feedstock, after admixing hydrogen in an amount of 356 to 3560 volumes of H ₂ , measured at 15 ° C and 1 atm, per volume of oil, measured at 15 ° C, is abbreviated below as V / V for simplicity, preferably at least 890 V / V, introduced in the reaction zone. The feedstock can be in the liquid, vapor or liquid-vapor phase, depending on the temperature, the pressure, the proportion of hydrogen and the boiling range of the feedstock to be processed. The hourly space velocity of the liquid as it passes through the reaction zone is above 0.2 and usually in the range 1.9 to 15.0. The hydrogen can be supplied in the form of a hydrogen-rich gas stream which is withdrawn from a separation zone operating at high pressure and low temperature and recycled. Excess hydrogen from, for example, a catalytic reforming plant can also be used. The reaction zone is usually operated under a pressure of 6.4 to 205 atmospheres. The catalyst bed inlet temperature is maintained in the range of 177 to 427 "C. Since the hydrocracking reactions are exothermic

is the reactor outlet temperature and temperature, respectively considerably higher at the bottom of the catalyst bed than at the inlet. The extent of the exothermic Heat generation, which is shown by the temperature rise along the catalyst bed, depends on the Type of fuel, the throughput of the hydrocarbon feed, the degree of conversion to lower-boiling hydrocarbons, etc. There is such a Kalalysatorbett inlet temperature in every! • "all chosen that the exothermic heat generated by the reactions that occur does not result in a Temperature at the outlet of the catalyst bed of over 482 ° C and preferably 454 ° C leads. It can also with a moving catalyst bed or with a catalyst slurry in which the catalyst, the hydrocarbons and hydrogen are mixed together and formed into a pulp passed through the reaction zone.

If, after a long period of operation, a Regeneration of the catalyst becomes appropriate, the catalyst can easily be treated in one oxidizing atmosphere at a temperature of 399 to 454 ° C with burning off of coke and others regenerate heavy hydrocarbonaceous substances. The catalyst can then be in place and Place again subjected to the reduction treatment with hydrogen at a temperature of 538 to 649 ° C and, if desired, thereafter in the same manner as above for fresh catalyst has been described, be sulfided.

The drawing illustrates technical advantages of the catalyst in hydrocracking, such as that will be explained below.

Example with comparison searches

There were three silica-alumina-nickel-tungsten catalysts manufactured and tested. Each catalyst contained 8% nickel and 18% Tungsten. The catalysts differ in that the carrier is 40, 50 or 63 percent by weight Contained aluminum oxide. The mixed-gelled silica-alumina carrier was made for each Catalyst according to the oil drop method described above by joint gelling of the silicon dioxide-producing compound and the aluminum oxide supplying compound produced, these compounds each in such amounts with one another blended and blended to form a final carrier with the specified alumina content revealed. The final carrier was in the shape of a ball 1.6 mm in diameter.

The mixed carrier, which contained 40 percent by weight of aluminum oxide, was washed with an aqueous Impregnated solution of nickel nitrate and ammonium octatungstate. The impregnated balls were dried and then oxidized at a temperature of 593 "C. The concentrations of the metal salts in the aqueous impregnation solution were chosen so that a final catalyst with the indicated content of 8 percent by weight nickel and 18 percent by weight tungsten. The one made in this way finished hydrocracking catalyst is referred to as catalyst 1 hereinafter. ι

The mixed-gelled carrier containing 50 weight percent alumina became exactly the same Manner as described above for the catalyst 1, processed. This catalyst, de: also 8 percent by weight nickel and 18 percent by weight percent tungsten is hereinafter referred to as catalyst 2.

The mixed-gelled carrier containing 63 percent by weight of aluminum oxide was exactly the same Way, as indicated above for the catalysts 1 and 2, processed. The finished catalyst which in turn contained 8 percent by weight nickel and 18 percent by weight tungsten, is below al; Catalyst 3 designated.

The three catalysts were then, separately from one another but in exactly the same way, for the Hydrocracking of a light vacuum gas oil, the properties of which are summarized in Table I. used. The catalysts 1 and 3 represent comparative catalysts, the catalyst 2 corresponds the rules of the invention.

Table I.
Properties of light vacuum gas oil

Specific weight, at 15.6 ° C 0.841 Distillation, "C Start of boiling 288 10% 335 30% 365 50% 380 70 % 394 90% 419 End of boiling 457 Total sulfur, wt% 0.07 Total nitrogen, w / w% 0.044 Aromatics, vol .-% 12.7 Paraffins and naphthenes,% by volume 87.3 Pour point, "C 27

In each case the light vacuum gas oil was at a reactor pressure of 137 atm, a liquid hourly space velocity of 1.0, a hydrogen circulation of 1700 V / V and a catalyst bed temperature necessary to produce a product boiling up from 157 ° C with a Pour point of - 21 ° C was required processed. The comparison catalyst 1 required a catalyst temperature of 406 ° C, the catalyst 2 According to the invention, a catalyst temperature of 401 ° C., and the comparative catalyst 3 has a catalyst temperature of 415 ° C in order to achieve the prescribed product properties. These values are shown in Table II below and graphically in the accompanying drawing.

Table II
Testing for hydrocracking activity

catalyst

1 (Vcr- 2 (equation) invention)

3 (comparison)

Aluminum oxide content 40 50 63

Required reactor 406 401 415

temperature for one
Pour point of -21 "C,
° C

From the expansions of 'Table I and the drawing it can be seen that for the three catalysts of increasing Content of aluminum oxide in the carrier produced by joint gelling in spite of this otherwise completely identical catalyst production, composition and testing no par-

allclity between the alumina content of the mixed-gelled carrier and the required catalyst bed temperature, which is characteristic of the efficiency of the catalytic converter, exists, but an abrupt improvement in the range of the aluminum oxide content prescribed according to the invention of the mixed gelled carrier material occurs. This is based on a comparison with the catalysts 1, 2 and 3 obtained results, i.e. H. the required catalyst bed temperatures of 406 ° C or 401 ° C or 415 ° C for bringing about the prescribed product properties, clearly emerged. In the drawing, points 1, 2 and 3 indicate those achieved with catalyst 1, 2 and 3, respectively Results. The resulting curve 4 shows

10

clearly the critical importance of maintaining an aluminum oxide content in the joint gelation of the carrier within the prescribed range of 43 to 57 percent by weight to a catalyst to generate optimal activity and accordingly a liquid product with the desired Achieve properties at the lowest possible catalyst bed temperature. The ones with a decrease the technical and economic advantages associated with the required catalyst bed temperature are familiar to the person skilled in the art and require no further explanation, as are the advantages of simple preparation of the support by joint gelation of the silicon dioxide-providing compound and the alumina-producing compound.

1 sheet of drawings

Claims (2)

Patent claims: 1. Catalyst with a nickel component and a tungsten component on a silicon dioxide-aluminum oxide carrier, obtained by preparing the support from a compound which yields silicon dioxide and from an aluminum oxide delivering compound and optionally washing, drying and calcining of the resulting Carrier, impregnation of the carrier with the nickel component and the tungsten component, in particular using an aqueous solution of a nickel salt and a tungsten salt, and drying and calcining the impregnated support at elevated temperatures in an oxidizing atmosphere, characterized in that it by joint gelling the silica-generating compound and the alumina-generating compound in such a proportion that the finished support 43 to 57 percent by weight of aluminum oxide and contains 57 to 43 weight percent silica, impregnating the resulting Carrier with 2 to 10 weight percent of the nickel component and 8 to 20 weight percent of the Tungsten component, calculated as metals and based on the final catalyst composition, Drying the impregnated support at a temperature of 93 to 260 ° C. and calcining at a temperature of 371 to 649 ° C and optionally reducing at a temperature from 371 to 538 ° C in the presence of hydrogen. 2. Use of the catalyst according to claim 1 for the hydrocracking of hydrocarbons.